Greatest common substringShortest Longest Common Subsequence CodeDecompose a StringGiven a string find the substring which appears most oftenFind Patterns in StringsShortest Longest Common Subsequence CodeMaximal Substring ConstructionVisualize the greatest common divisorShortest Unique SubstringAs Easy As A-B-CFind the original string, without the repetition without the repetition in the middleThe Third String

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Longest common substring in linear time



Greatest common substring


Shortest Longest Common Subsequence CodeDecompose a StringGiven a string find the substring which appears most oftenFind Patterns in StringsShortest Longest Common Subsequence CodeMaximal Substring ConstructionVisualize the greatest common divisorShortest Unique SubstringAs Easy As A-B-CFind the original string, without the repetition without the repetition in the middleThe Third String













5












$begingroup$


Create a program or function which takes a list of strings as input, and outputs the longest string that is a substring of all input strings. If there are several substrings of equal length, and no longer substring, output any one of them.



  • This may mean outputting the empty string.

  • If there are several valid outputs, you may output any one of them. You are not required to give consistent outpput for a given input so long as the output is always valid.

  • There will always be at least one string in the input, but there might not be a non-empty string.

  • All printable ASCII characters may appear in the input. You may assume those are the only characters that appear.

  • You may take input or produce output by any of the default methods.


  • Standard loopholes aren't allowed.

  • This is code-golf - the fewer bytes of code, the better.

Test cases:



[Inputs] -> [Valid outputs (choose one)]



["hello", "'ello"] -> ["ello"]
["very", "much", "different"] -> [""]
["empty", "", "STRING"] -> [""]
["identical", "identical"] -> ["identical"]
["string", "stRIng"] -> ["st", "ng"]
["this one", "is a substring of this one"] -> ["this one"]
["just one"] -> ["just one"]
["", "", ""] -> [""]
["many outputs", "stuptuo ynam"] -> ["m", "a", "n", "y", " ", "o", "u", "t", "p", "s"]
["many inputs", "any inputs", "ny iii", "yanny"] -> ["ny"]
["%%not&", "ju&#st", "[&]alpha_numeric"] -> ["&"]









share|improve this question











$endgroup$











  • $begingroup$
    Possible duplicate
    $endgroup$
    – Adám
    2 hours ago










  • $begingroup$
    @Adám That question asks for the longest common subsequence, not substring.
    $endgroup$
    – Doorknob
    2 hours ago






  • 1




    $begingroup$
    Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
    $endgroup$
    – Embodiment of Ignorance
    1 hour ago










  • $begingroup$
    @EmbodimentofIgnorance All printable ASCII characters can appear in the input.
    $endgroup$
    – Sara J
    1 hour ago










  • $begingroup$
    @JoKing Yeah, it can. Apparently I'm too tired for this.
    $endgroup$
    – Sara J
    24 mins ago
















5












$begingroup$


Create a program or function which takes a list of strings as input, and outputs the longest string that is a substring of all input strings. If there are several substrings of equal length, and no longer substring, output any one of them.



  • This may mean outputting the empty string.

  • If there are several valid outputs, you may output any one of them. You are not required to give consistent outpput for a given input so long as the output is always valid.

  • There will always be at least one string in the input, but there might not be a non-empty string.

  • All printable ASCII characters may appear in the input. You may assume those are the only characters that appear.

  • You may take input or produce output by any of the default methods.


  • Standard loopholes aren't allowed.

  • This is code-golf - the fewer bytes of code, the better.

Test cases:



[Inputs] -> [Valid outputs (choose one)]



["hello", "'ello"] -> ["ello"]
["very", "much", "different"] -> [""]
["empty", "", "STRING"] -> [""]
["identical", "identical"] -> ["identical"]
["string", "stRIng"] -> ["st", "ng"]
["this one", "is a substring of this one"] -> ["this one"]
["just one"] -> ["just one"]
["", "", ""] -> [""]
["many outputs", "stuptuo ynam"] -> ["m", "a", "n", "y", " ", "o", "u", "t", "p", "s"]
["many inputs", "any inputs", "ny iii", "yanny"] -> ["ny"]
["%%not&", "ju&#st", "[&]alpha_numeric"] -> ["&"]









share|improve this question











$endgroup$











  • $begingroup$
    Possible duplicate
    $endgroup$
    – Adám
    2 hours ago










  • $begingroup$
    @Adám That question asks for the longest common subsequence, not substring.
    $endgroup$
    – Doorknob
    2 hours ago






  • 1




    $begingroup$
    Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
    $endgroup$
    – Embodiment of Ignorance
    1 hour ago










  • $begingroup$
    @EmbodimentofIgnorance All printable ASCII characters can appear in the input.
    $endgroup$
    – Sara J
    1 hour ago










  • $begingroup$
    @JoKing Yeah, it can. Apparently I'm too tired for this.
    $endgroup$
    – Sara J
    24 mins ago














5












5








5





$begingroup$


Create a program or function which takes a list of strings as input, and outputs the longest string that is a substring of all input strings. If there are several substrings of equal length, and no longer substring, output any one of them.



  • This may mean outputting the empty string.

  • If there are several valid outputs, you may output any one of them. You are not required to give consistent outpput for a given input so long as the output is always valid.

  • There will always be at least one string in the input, but there might not be a non-empty string.

  • All printable ASCII characters may appear in the input. You may assume those are the only characters that appear.

  • You may take input or produce output by any of the default methods.


  • Standard loopholes aren't allowed.

  • This is code-golf - the fewer bytes of code, the better.

Test cases:



[Inputs] -> [Valid outputs (choose one)]



["hello", "'ello"] -> ["ello"]
["very", "much", "different"] -> [""]
["empty", "", "STRING"] -> [""]
["identical", "identical"] -> ["identical"]
["string", "stRIng"] -> ["st", "ng"]
["this one", "is a substring of this one"] -> ["this one"]
["just one"] -> ["just one"]
["", "", ""] -> [""]
["many outputs", "stuptuo ynam"] -> ["m", "a", "n", "y", " ", "o", "u", "t", "p", "s"]
["many inputs", "any inputs", "ny iii", "yanny"] -> ["ny"]
["%%not&", "ju&#st", "[&]alpha_numeric"] -> ["&"]









share|improve this question











$endgroup$




Create a program or function which takes a list of strings as input, and outputs the longest string that is a substring of all input strings. If there are several substrings of equal length, and no longer substring, output any one of them.



  • This may mean outputting the empty string.

  • If there are several valid outputs, you may output any one of them. You are not required to give consistent outpput for a given input so long as the output is always valid.

  • There will always be at least one string in the input, but there might not be a non-empty string.

  • All printable ASCII characters may appear in the input. You may assume those are the only characters that appear.

  • You may take input or produce output by any of the default methods.


  • Standard loopholes aren't allowed.

  • This is code-golf - the fewer bytes of code, the better.

Test cases:



[Inputs] -> [Valid outputs (choose one)]



["hello", "'ello"] -> ["ello"]
["very", "much", "different"] -> [""]
["empty", "", "STRING"] -> [""]
["identical", "identical"] -> ["identical"]
["string", "stRIng"] -> ["st", "ng"]
["this one", "is a substring of this one"] -> ["this one"]
["just one"] -> ["just one"]
["", "", ""] -> [""]
["many outputs", "stuptuo ynam"] -> ["m", "a", "n", "y", " ", "o", "u", "t", "p", "s"]
["many inputs", "any inputs", "ny iii", "yanny"] -> ["ny"]
["%%not&", "ju&#st", "[&]alpha_numeric"] -> ["&"]






code-golf string subsequence






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 6 mins ago







Sara J

















asked 3 hours ago









Sara JSara J

1765




1765











  • $begingroup$
    Possible duplicate
    $endgroup$
    – Adám
    2 hours ago










  • $begingroup$
    @Adám That question asks for the longest common subsequence, not substring.
    $endgroup$
    – Doorknob
    2 hours ago






  • 1




    $begingroup$
    Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
    $endgroup$
    – Embodiment of Ignorance
    1 hour ago










  • $begingroup$
    @EmbodimentofIgnorance All printable ASCII characters can appear in the input.
    $endgroup$
    – Sara J
    1 hour ago










  • $begingroup$
    @JoKing Yeah, it can. Apparently I'm too tired for this.
    $endgroup$
    – Sara J
    24 mins ago

















  • $begingroup$
    Possible duplicate
    $endgroup$
    – Adám
    2 hours ago










  • $begingroup$
    @Adám That question asks for the longest common subsequence, not substring.
    $endgroup$
    – Doorknob
    2 hours ago






  • 1




    $begingroup$
    Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
    $endgroup$
    – Embodiment of Ignorance
    1 hour ago










  • $begingroup$
    @EmbodimentofIgnorance All printable ASCII characters can appear in the input.
    $endgroup$
    – Sara J
    1 hour ago










  • $begingroup$
    @JoKing Yeah, it can. Apparently I'm too tired for this.
    $endgroup$
    – Sara J
    24 mins ago
















$begingroup$
Possible duplicate
$endgroup$
– Adám
2 hours ago




$begingroup$
Possible duplicate
$endgroup$
– Adám
2 hours ago












$begingroup$
@Adám That question asks for the longest common subsequence, not substring.
$endgroup$
– Doorknob
2 hours ago




$begingroup$
@Adám That question asks for the longest common subsequence, not substring.
$endgroup$
– Doorknob
2 hours ago




1




1




$begingroup$
Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
$endgroup$
– Embodiment of Ignorance
1 hour ago




$begingroup$
Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
$endgroup$
– Embodiment of Ignorance
1 hour ago












$begingroup$
@EmbodimentofIgnorance All printable ASCII characters can appear in the input.
$endgroup$
– Sara J
1 hour ago




$begingroup$
@EmbodimentofIgnorance All printable ASCII characters can appear in the input.
$endgroup$
– Sara J
1 hour ago












$begingroup$
@JoKing Yeah, it can. Apparently I'm too tired for this.
$endgroup$
– Sara J
24 mins ago





$begingroup$
@JoKing Yeah, it can. Apparently I'm too tired for this.
$endgroup$
– Sara J
24 mins ago











8 Answers
8






active

oldest

votes


















1












$begingroup$


Python 3, 137 bytes





def a(b):c=[[d[f:e]for e in range(len(d)+1)for f in range(e+1)]for d in b];return max([i for i in c[0]if all(i in j for j in c)],key=len)


Try it online!






share|improve this answer










New contributor




Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






$endgroup$












  • $begingroup$
    You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
    $endgroup$
    – Shieru Asakoto
    2 hours ago










  • $begingroup$
    @ShieruAsakoto Oops yeah.
    $endgroup$
    – Artemis Fowl
    2 hours ago










  • $begingroup$
    @JoKing tio.run/…
    $endgroup$
    – Artemis Fowl
    1 hour ago










  • $begingroup$
    @JoKing The one currently in my answer is fine for all the test cases.
    $endgroup$
    – Artemis Fowl
    1 hour ago










  • $begingroup$
    Right, here's a fixed version of the 135 byte program
    $endgroup$
    – Jo King
    1 hour ago



















0












$begingroup$


Jelly, 12 bytes



Ẇ€œ&/LÐṀḢ¹L?


Try it online!



Last four bytes are there because of the requirement to only output one answer.






share|improve this answer









$endgroup$




















    0












    $begingroup$


    Brachylog (v2), 3 bytes



    sᵛw


    Try it online!



    Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



    Explanation



    sᵛw
    s Find a substring
    ᵛ of every element of the input; the same one for each
    w and output it.


    Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



    Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.






    share|improve this answer











    $endgroup$




















      0












      $begingroup$


      Perl 6, 62 bytes





      ~sort(-*.comb,keys [∩] .map(*.comb[^*X.. ^*+1]>>.join))[0]


      Try it online!



      I'm a little annoyed the Perl 6 can't do set operations on lists of lists, which is why there's an extra .comb and >> in there. Another annoying thing is that max can't take an function for how to compare items, meaning I have to user sort instead.






      share|improve this answer









      $endgroup$




















        0












        $begingroup$


        Japt v2.0a0, 24 bytes



        mã c f@eøXÃr@XÊ>YÊ?X:Y}P


        This is a mess. Why isn't there a max function for arrays in Japt?



        Try it online!






        share|improve this answer









        $endgroup$




















          0












          $begingroup$


          JavaScript (Node.js), 106 bytes



          This assumes presence of regex special characters.





          a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.indexOf(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


          Try it online!




          JavaScript (Node.js), 114 105 bytes



          This assumes absence of regex special characters.





          a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


          Try it online!



          Probably still golfable.






          share|improve this answer











          $endgroup$




















            0












            $begingroup$


            Zsh, 126 bytes





            for l in $@
            a=
            for i in 0..$[$#l**2]
            a+=($l[1+i/$#l,1+i%$#l])

            b=($$b-$a:*a)

            for i in $b
            (($#x<$#i))&&x=$i

            <<<$x


            Try it online!



            We read all possible substrings into $a, and then intersect the common elements of $a and $b. The construct $b-$a will only substitue $a on the first iteration: Even if $b is empty (no common strings), it is still set.



            for l in $@; 
            a= # empty a
            for i in 0..$[$#l**2]; # compound double loop using div/mod
            a+=( $l[1+i/$#l,1+i%$#l] ) # append to a all possible substrings of the given line

            b=( $$b-$a:*a )
            # $b-$a # if b is unset substitute $a
            # $ :*a # take common elements of $b-$a and $a
            # b=( ) # set b to those elements

            for i in $b; # for every common substring
            (( $#x < $#i ))&&x=$i # if the current word is longer, use it

            <<<$x # print to stdout





            share|improve this answer










            New contributor




            GammaFunction is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
            Check out our Code of Conduct.






            $endgroup$




















              0












              $begingroup$


              Python 2, 103 bytes





              lambda b:max(reduce(set.__and__,[d[f:e]for e in range(len(d)+2)for f in range(e)for d in b]),key=len)


              Try it online!



              This is an anonymous lambda that transforms each element into the set of all substrings, then reduces it by set intersection (set.__and__) and then returns the max element by length.






              share|improve this answer











              $endgroup$












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                8 Answers
                8






                active

                oldest

                votes








                8 Answers
                8






                active

                oldest

                votes









                active

                oldest

                votes






                active

                oldest

                votes









                1












                $begingroup$


                Python 3, 137 bytes





                def a(b):c=[[d[f:e]for e in range(len(d)+1)for f in range(e+1)]for d in b];return max([i for i in c[0]if all(i in j for j in c)],key=len)


                Try it online!






                share|improve this answer










                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






                $endgroup$












                • $begingroup$
                  You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                  $endgroup$
                  – Shieru Asakoto
                  2 hours ago










                • $begingroup$
                  @ShieruAsakoto Oops yeah.
                  $endgroup$
                  – Artemis Fowl
                  2 hours ago










                • $begingroup$
                  @JoKing tio.run/…
                  $endgroup$
                  – Artemis Fowl
                  1 hour ago










                • $begingroup$
                  @JoKing The one currently in my answer is fine for all the test cases.
                  $endgroup$
                  – Artemis Fowl
                  1 hour ago










                • $begingroup$
                  Right, here's a fixed version of the 135 byte program
                  $endgroup$
                  – Jo King
                  1 hour ago
















                1












                $begingroup$


                Python 3, 137 bytes





                def a(b):c=[[d[f:e]for e in range(len(d)+1)for f in range(e+1)]for d in b];return max([i for i in c[0]if all(i in j for j in c)],key=len)


                Try it online!






                share|improve this answer










                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






                $endgroup$












                • $begingroup$
                  You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                  $endgroup$
                  – Shieru Asakoto
                  2 hours ago










                • $begingroup$
                  @ShieruAsakoto Oops yeah.
                  $endgroup$
                  – Artemis Fowl
                  2 hours ago










                • $begingroup$
                  @JoKing tio.run/…
                  $endgroup$
                  – Artemis Fowl
                  1 hour ago










                • $begingroup$
                  @JoKing The one currently in my answer is fine for all the test cases.
                  $endgroup$
                  – Artemis Fowl
                  1 hour ago










                • $begingroup$
                  Right, here's a fixed version of the 135 byte program
                  $endgroup$
                  – Jo King
                  1 hour ago














                1












                1








                1





                $begingroup$


                Python 3, 137 bytes





                def a(b):c=[[d[f:e]for e in range(len(d)+1)for f in range(e+1)]for d in b];return max([i for i in c[0]if all(i in j for j in c)],key=len)


                Try it online!






                share|improve this answer










                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






                $endgroup$




                Python 3, 137 bytes





                def a(b):c=[[d[f:e]for e in range(len(d)+1)for f in range(e+1)]for d in b];return max([i for i in c[0]if all(i in j for j in c)],key=len)


                Try it online!







                share|improve this answer










                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.









                share|improve this answer



                share|improve this answer








                edited 1 hour ago





















                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.









                answered 2 hours ago









                Artemis FowlArtemis Fowl

                1114




                1114




                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.





                New contributor





                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.











                • $begingroup$
                  You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                  $endgroup$
                  – Shieru Asakoto
                  2 hours ago










                • $begingroup$
                  @ShieruAsakoto Oops yeah.
                  $endgroup$
                  – Artemis Fowl
                  2 hours ago










                • $begingroup$
                  @JoKing tio.run/…
                  $endgroup$
                  – Artemis Fowl
                  1 hour ago










                • $begingroup$
                  @JoKing The one currently in my answer is fine for all the test cases.
                  $endgroup$
                  – Artemis Fowl
                  1 hour ago










                • $begingroup$
                  Right, here's a fixed version of the 135 byte program
                  $endgroup$
                  – Jo King
                  1 hour ago

















                • $begingroup$
                  You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                  $endgroup$
                  – Shieru Asakoto
                  2 hours ago










                • $begingroup$
                  @ShieruAsakoto Oops yeah.
                  $endgroup$
                  – Artemis Fowl
                  2 hours ago










                • $begingroup$
                  @JoKing tio.run/…
                  $endgroup$
                  – Artemis Fowl
                  1 hour ago










                • $begingroup$
                  @JoKing The one currently in my answer is fine for all the test cases.
                  $endgroup$
                  – Artemis Fowl
                  1 hour ago










                • $begingroup$
                  Right, here's a fixed version of the 135 byte program
                  $endgroup$
                  – Jo King
                  1 hour ago
















                $begingroup$
                You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                $endgroup$
                – Shieru Asakoto
                2 hours ago




                $begingroup$
                You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                $endgroup$
                – Shieru Asakoto
                2 hours ago












                $begingroup$
                @ShieruAsakoto Oops yeah.
                $endgroup$
                – Artemis Fowl
                2 hours ago




                $begingroup$
                @ShieruAsakoto Oops yeah.
                $endgroup$
                – Artemis Fowl
                2 hours ago












                $begingroup$
                @JoKing tio.run/…
                $endgroup$
                – Artemis Fowl
                1 hour ago




                $begingroup$
                @JoKing tio.run/…
                $endgroup$
                – Artemis Fowl
                1 hour ago












                $begingroup$
                @JoKing The one currently in my answer is fine for all the test cases.
                $endgroup$
                – Artemis Fowl
                1 hour ago




                $begingroup$
                @JoKing The one currently in my answer is fine for all the test cases.
                $endgroup$
                – Artemis Fowl
                1 hour ago












                $begingroup$
                Right, here's a fixed version of the 135 byte program
                $endgroup$
                – Jo King
                1 hour ago





                $begingroup$
                Right, here's a fixed version of the 135 byte program
                $endgroup$
                – Jo King
                1 hour ago












                0












                $begingroup$


                Jelly, 12 bytes



                Ẇ€œ&/LÐṀḢ¹L?


                Try it online!



                Last four bytes are there because of the requirement to only output one answer.






                share|improve this answer









                $endgroup$

















                  0












                  $begingroup$


                  Jelly, 12 bytes



                  Ẇ€œ&/LÐṀḢ¹L?


                  Try it online!



                  Last four bytes are there because of the requirement to only output one answer.






                  share|improve this answer









                  $endgroup$















                    0












                    0








                    0





                    $begingroup$


                    Jelly, 12 bytes



                    Ẇ€œ&/LÐṀḢ¹L?


                    Try it online!



                    Last four bytes are there because of the requirement to only output one answer.






                    share|improve this answer









                    $endgroup$




                    Jelly, 12 bytes



                    Ẇ€œ&/LÐṀḢ¹L?


                    Try it online!



                    Last four bytes are there because of the requirement to only output one answer.







                    share|improve this answer












                    share|improve this answer



                    share|improve this answer










                    answered 2 hours ago









                    Nick KennedyNick Kennedy

                    92147




                    92147





















                        0












                        $begingroup$


                        Brachylog (v2), 3 bytes



                        sᵛw


                        Try it online!



                        Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



                        Explanation



                        sᵛw
                        s Find a substring
                        ᵛ of every element of the input; the same one for each
                        w and output it.


                        Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



                        Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.






                        share|improve this answer











                        $endgroup$

















                          0












                          $begingroup$


                          Brachylog (v2), 3 bytes



                          sᵛw


                          Try it online!



                          Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



                          Explanation



                          sᵛw
                          s Find a substring
                          ᵛ of every element of the input; the same one for each
                          w and output it.


                          Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



                          Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.






                          share|improve this answer











                          $endgroup$















                            0












                            0








                            0





                            $begingroup$


                            Brachylog (v2), 3 bytes



                            sᵛw


                            Try it online!



                            Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



                            Explanation



                            sᵛw
                            s Find a substring
                            ᵛ of every element of the input; the same one for each
                            w and output it.


                            Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



                            Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.






                            share|improve this answer











                            $endgroup$




                            Brachylog (v2), 3 bytes



                            sᵛw


                            Try it online!



                            Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



                            Explanation



                            sᵛw
                            s Find a substring
                            ᵛ of every element of the input; the same one for each
                            w and output it.


                            Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



                            Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.







                            share|improve this answer














                            share|improve this answer



                            share|improve this answer








                            answered 1 hour ago


























                            community wiki





                            ais523






















                                0












                                $begingroup$


                                Perl 6, 62 bytes





                                ~sort(-*.comb,keys [∩] .map(*.comb[^*X.. ^*+1]>>.join))[0]


                                Try it online!



                                I'm a little annoyed the Perl 6 can't do set operations on lists of lists, which is why there's an extra .comb and >> in there. Another annoying thing is that max can't take an function for how to compare items, meaning I have to user sort instead.






                                share|improve this answer









                                $endgroup$

















                                  0












                                  $begingroup$


                                  Perl 6, 62 bytes





                                  ~sort(-*.comb,keys [∩] .map(*.comb[^*X.. ^*+1]>>.join))[0]


                                  Try it online!



                                  I'm a little annoyed the Perl 6 can't do set operations on lists of lists, which is why there's an extra .comb and >> in there. Another annoying thing is that max can't take an function for how to compare items, meaning I have to user sort instead.






                                  share|improve this answer









                                  $endgroup$















                                    0












                                    0








                                    0





                                    $begingroup$


                                    Perl 6, 62 bytes





                                    ~sort(-*.comb,keys [∩] .map(*.comb[^*X.. ^*+1]>>.join))[0]


                                    Try it online!



                                    I'm a little annoyed the Perl 6 can't do set operations on lists of lists, which is why there's an extra .comb and >> in there. Another annoying thing is that max can't take an function for how to compare items, meaning I have to user sort instead.






                                    share|improve this answer









                                    $endgroup$




                                    Perl 6, 62 bytes





                                    ~sort(-*.comb,keys [∩] .map(*.comb[^*X.. ^*+1]>>.join))[0]


                                    Try it online!



                                    I'm a little annoyed the Perl 6 can't do set operations on lists of lists, which is why there's an extra .comb and >> in there. Another annoying thing is that max can't take an function for how to compare items, meaning I have to user sort instead.







                                    share|improve this answer












                                    share|improve this answer



                                    share|improve this answer










                                    answered 1 hour ago









                                    Jo KingJo King

                                    25.3k361129




                                    25.3k361129





















                                        0












                                        $begingroup$


                                        Japt v2.0a0, 24 bytes



                                        mã c f@eøXÃr@XÊ>YÊ?X:Y}P


                                        This is a mess. Why isn't there a max function for arrays in Japt?



                                        Try it online!






                                        share|improve this answer









                                        $endgroup$

















                                          0












                                          $begingroup$


                                          Japt v2.0a0, 24 bytes



                                          mã c f@eøXÃr@XÊ>YÊ?X:Y}P


                                          This is a mess. Why isn't there a max function for arrays in Japt?



                                          Try it online!






                                          share|improve this answer









                                          $endgroup$















                                            0












                                            0








                                            0





                                            $begingroup$


                                            Japt v2.0a0, 24 bytes



                                            mã c f@eøXÃr@XÊ>YÊ?X:Y}P


                                            This is a mess. Why isn't there a max function for arrays in Japt?



                                            Try it online!






                                            share|improve this answer









                                            $endgroup$




                                            Japt v2.0a0, 24 bytes



                                            mã c f@eøXÃr@XÊ>YÊ?X:Y}P


                                            This is a mess. Why isn't there a max function for arrays in Japt?



                                            Try it online!







                                            share|improve this answer












                                            share|improve this answer



                                            share|improve this answer










                                            answered 59 mins ago









                                            Embodiment of IgnoranceEmbodiment of Ignorance

                                            2,138125




                                            2,138125





















                                                0












                                                $begingroup$


                                                JavaScript (Node.js), 106 bytes



                                                This assumes presence of regex special characters.





                                                a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.indexOf(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                                                Try it online!




                                                JavaScript (Node.js), 114 105 bytes



                                                This assumes absence of regex special characters.





                                                a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                                                Try it online!



                                                Probably still golfable.






                                                share|improve this answer











                                                $endgroup$

















                                                  0












                                                  $begingroup$


                                                  JavaScript (Node.js), 106 bytes



                                                  This assumes presence of regex special characters.





                                                  a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.indexOf(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                                                  Try it online!




                                                  JavaScript (Node.js), 114 105 bytes



                                                  This assumes absence of regex special characters.





                                                  a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                                                  Try it online!



                                                  Probably still golfable.






                                                  share|improve this answer











                                                  $endgroup$















                                                    0












                                                    0








                                                    0





                                                    $begingroup$


                                                    JavaScript (Node.js), 106 bytes



                                                    This assumes presence of regex special characters.





                                                    a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.indexOf(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                                                    Try it online!




                                                    JavaScript (Node.js), 114 105 bytes



                                                    This assumes absence of regex special characters.





                                                    a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                                                    Try it online!



                                                    Probably still golfable.






                                                    share|improve this answer











                                                    $endgroup$




                                                    JavaScript (Node.js), 106 bytes



                                                    This assumes presence of regex special characters.





                                                    a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.indexOf(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                                                    Try it online!




                                                    JavaScript (Node.js), 114 105 bytes



                                                    This assumes absence of regex special characters.





                                                    a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                                                    Try it online!



                                                    Probably still golfable.







                                                    share|improve this answer














                                                    share|improve this answer



                                                    share|improve this answer








                                                    edited 50 mins ago

























                                                    answered 2 hours ago









                                                    Shieru AsakotoShieru Asakoto

                                                    2,750317




                                                    2,750317





















                                                        0












                                                        $begingroup$


                                                        Zsh, 126 bytes





                                                        for l in $@
                                                        a=
                                                        for i in 0..$[$#l**2]
                                                        a+=($l[1+i/$#l,1+i%$#l])

                                                        b=($$b-$a:*a)

                                                        for i in $b
                                                        (($#x<$#i))&&x=$i

                                                        <<<$x


                                                        Try it online!



                                                        We read all possible substrings into $a, and then intersect the common elements of $a and $b. The construct $b-$a will only substitue $a on the first iteration: Even if $b is empty (no common strings), it is still set.



                                                        for l in $@; 
                                                        a= # empty a
                                                        for i in 0..$[$#l**2]; # compound double loop using div/mod
                                                        a+=( $l[1+i/$#l,1+i%$#l] ) # append to a all possible substrings of the given line

                                                        b=( $$b-$a:*a )
                                                        # $b-$a # if b is unset substitute $a
                                                        # $ :*a # take common elements of $b-$a and $a
                                                        # b=( ) # set b to those elements

                                                        for i in $b; # for every common substring
                                                        (( $#x < $#i ))&&x=$i # if the current word is longer, use it

                                                        <<<$x # print to stdout





                                                        share|improve this answer










                                                        New contributor




                                                        GammaFunction is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                                        Check out our Code of Conduct.






                                                        $endgroup$

















                                                          0












                                                          $begingroup$


                                                          Zsh, 126 bytes





                                                          for l in $@
                                                          a=
                                                          for i in 0..$[$#l**2]
                                                          a+=($l[1+i/$#l,1+i%$#l])

                                                          b=($$b-$a:*a)

                                                          for i in $b
                                                          (($#x<$#i))&&x=$i

                                                          <<<$x


                                                          Try it online!



                                                          We read all possible substrings into $a, and then intersect the common elements of $a and $b. The construct $b-$a will only substitue $a on the first iteration: Even if $b is empty (no common strings), it is still set.



                                                          for l in $@; 
                                                          a= # empty a
                                                          for i in 0..$[$#l**2]; # compound double loop using div/mod
                                                          a+=( $l[1+i/$#l,1+i%$#l] ) # append to a all possible substrings of the given line

                                                          b=( $$b-$a:*a )
                                                          # $b-$a # if b is unset substitute $a
                                                          # $ :*a # take common elements of $b-$a and $a
                                                          # b=( ) # set b to those elements

                                                          for i in $b; # for every common substring
                                                          (( $#x < $#i ))&&x=$i # if the current word is longer, use it

                                                          <<<$x # print to stdout





                                                          share|improve this answer










                                                          New contributor




                                                          GammaFunction is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                                          Check out our Code of Conduct.






                                                          $endgroup$















                                                            0












                                                            0








                                                            0





                                                            $begingroup$


                                                            Zsh, 126 bytes





                                                            for l in $@
                                                            a=
                                                            for i in 0..$[$#l**2]
                                                            a+=($l[1+i/$#l,1+i%$#l])

                                                            b=($$b-$a:*a)

                                                            for i in $b
                                                            (($#x<$#i))&&x=$i

                                                            <<<$x


                                                            Try it online!



                                                            We read all possible substrings into $a, and then intersect the common elements of $a and $b. The construct $b-$a will only substitue $a on the first iteration: Even if $b is empty (no common strings), it is still set.



                                                            for l in $@; 
                                                            a= # empty a
                                                            for i in 0..$[$#l**2]; # compound double loop using div/mod
                                                            a+=( $l[1+i/$#l,1+i%$#l] ) # append to a all possible substrings of the given line

                                                            b=( $$b-$a:*a )
                                                            # $b-$a # if b is unset substitute $a
                                                            # $ :*a # take common elements of $b-$a and $a
                                                            # b=( ) # set b to those elements

                                                            for i in $b; # for every common substring
                                                            (( $#x < $#i ))&&x=$i # if the current word is longer, use it

                                                            <<<$x # print to stdout





                                                            share|improve this answer










                                                            New contributor




                                                            GammaFunction is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                                            Check out our Code of Conduct.






                                                            $endgroup$




                                                            Zsh, 126 bytes





                                                            for l in $@
                                                            a=
                                                            for i in 0..$[$#l**2]
                                                            a+=($l[1+i/$#l,1+i%$#l])

                                                            b=($$b-$a:*a)

                                                            for i in $b
                                                            (($#x<$#i))&&x=$i

                                                            <<<$x


                                                            Try it online!



                                                            We read all possible substrings into $a, and then intersect the common elements of $a and $b. The construct $b-$a will only substitue $a on the first iteration: Even if $b is empty (no common strings), it is still set.



                                                            for l in $@; 
                                                            a= # empty a
                                                            for i in 0..$[$#l**2]; # compound double loop using div/mod
                                                            a+=( $l[1+i/$#l,1+i%$#l] ) # append to a all possible substrings of the given line

                                                            b=( $$b-$a:*a )
                                                            # $b-$a # if b is unset substitute $a
                                                            # $ :*a # take common elements of $b-$a and $a
                                                            # b=( ) # set b to those elements

                                                            for i in $b; # for every common substring
                                                            (( $#x < $#i ))&&x=$i # if the current word is longer, use it

                                                            <<<$x # print to stdout






                                                            share|improve this answer










                                                            New contributor




                                                            GammaFunction is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                                            Check out our Code of Conduct.









                                                            share|improve this answer



                                                            share|improve this answer








                                                            edited 43 mins ago





















                                                            New contributor




                                                            GammaFunction is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                                            Check out our Code of Conduct.









                                                            answered 52 mins ago









                                                            GammaFunctionGammaFunction

                                                            615




                                                            615




                                                            New contributor




                                                            GammaFunction is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                                            Check out our Code of Conduct.





                                                            New contributor





                                                            GammaFunction is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                                            Check out our Code of Conduct.






                                                            GammaFunction is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                                                            Check out our Code of Conduct.





















                                                                0












                                                                $begingroup$


                                                                Python 2, 103 bytes





                                                                lambda b:max(reduce(set.__and__,[d[f:e]for e in range(len(d)+2)for f in range(e)for d in b]),key=len)


                                                                Try it online!



                                                                This is an anonymous lambda that transforms each element into the set of all substrings, then reduces it by set intersection (set.__and__) and then returns the max element by length.






                                                                share|improve this answer











                                                                $endgroup$

















                                                                  0












                                                                  $begingroup$


                                                                  Python 2, 103 bytes





                                                                  lambda b:max(reduce(set.__and__,[d[f:e]for e in range(len(d)+2)for f in range(e)for d in b]),key=len)


                                                                  Try it online!



                                                                  This is an anonymous lambda that transforms each element into the set of all substrings, then reduces it by set intersection (set.__and__) and then returns the max element by length.






                                                                  share|improve this answer











                                                                  $endgroup$















                                                                    0












                                                                    0








                                                                    0





                                                                    $begingroup$


                                                                    Python 2, 103 bytes





                                                                    lambda b:max(reduce(set.__and__,[d[f:e]for e in range(len(d)+2)for f in range(e)for d in b]),key=len)


                                                                    Try it online!



                                                                    This is an anonymous lambda that transforms each element into the set of all substrings, then reduces it by set intersection (set.__and__) and then returns the max element by length.






                                                                    share|improve this answer











                                                                    $endgroup$




                                                                    Python 2, 103 bytes





                                                                    lambda b:max(reduce(set.__and__,[d[f:e]for e in range(len(d)+2)for f in range(e)for d in b]),key=len)


                                                                    Try it online!



                                                                    This is an anonymous lambda that transforms each element into the set of all substrings, then reduces it by set intersection (set.__and__) and then returns the max element by length.







                                                                    share|improve this answer














                                                                    share|improve this answer



                                                                    share|improve this answer








                                                                    edited 39 mins ago

























                                                                    answered 51 mins ago









                                                                    Jo KingJo King

                                                                    25.3k361129




                                                                    25.3k361129



























                                                                        draft saved

                                                                        draft discarded
















































                                                                        If this is an answer to a challenge…



                                                                        • …Be sure to follow the challenge specification. However, please refrain from exploiting obvious loopholes. Answers abusing any of the standard loopholes are considered invalid. If you think a specification is unclear or underspecified, comment on the question instead.


                                                                        • …Try to optimize your score. For instance, answers to code-golf challenges should attempt to be as short as possible. You can always include a readable version of the code in addition to the competitive one.
                                                                          Explanations of your answer make it more interesting to read and are very much encouraged.


                                                                        • …Include a short header which indicates the language(s) of your code and its score, as defined by the challenge.


                                                                        More generally…



                                                                        • …Please make sure to answer the question and provide sufficient detail.


                                                                        • …Avoid asking for help, clarification or responding to other answers (use comments instead).




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